linux-kernel - Re: [PATCH RFC 1/7] x86/virt/tdx: Add SEAMCALL wrapper to enter/exit TDX guest

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Message-ID: <83defc08-c05f-438d-9c64-a46f4112333c@intel.com>
Date: Fri, 22 Nov 2024 08:26:56 -0800
From: Dave Hansen <dave.hansen@...el.com>
To: Adrian Hunter <adrian.hunter@...el.com>, pbonzini@...hat.com,
 seanjc@...gle.com, kvm@...r.kernel.org, dave.hansen@...ux.intel.com
Cc: rick.p.edgecombe@...el.com, kai.huang@...el.com,
 reinette.chatre@...el.com, xiaoyao.li@...el.com,
 tony.lindgren@...ux.intel.com, binbin.wu@...ux.intel.com,
 dmatlack@...gle.com, isaku.yamahata@...el.com, nik.borisov@...e.com,
 linux-kernel@...r.kernel.org, x86@...nel.org, yan.y.zhao@...el.com,
 chao.gao@...el.com, weijiang.yang@...el.com
Subject: Re: [PATCH RFC 1/7] x86/virt/tdx: Add SEAMCALL wrapper to enter/exit
 TDX guest

On 11/21/24 12:14, Adrian Hunter wrote:
> +u64 tdh_vp_enter(u64 tdvpr, struct tdx_module_args *args)
> +{
> +	args->rcx = tdvpr;
> +
> +	return __seamcall_saved_ret(TDH_VP_ENTER, args);
> +}
> +EXPORT_SYMBOL_GPL(tdh_vp_enter);

I made a similar comment on another series, but it stands here too: the
typing of this wrappers really needs a closer look. Passing u64's around
everywhere means zero type safety.

Type safety is the reason that we have types like pte_t and pgprot_t in
mm code even though they're really just longs (most of the time).

I'd suggest keeping the tdx_td_page type as long as possible, probably
until (for example) the ->rcx assignment, like this:

	args->rcx = td_page.pa;